Can filling apparatus generally comprises means for rotating the can beneath a head part on which there is a driven plate rotatable about a vertical axis. The rotary plate carries a pair of calender rolls rotatable about generally horizontal axes and arranged to grip the sliver and feed it into the can at a controlled speed, depositing it in continuous cycloidal loops in the can.
Can filling apparatus of the general type with which the present invention is concerned is disclosed in EP-OS 175 072, laid-open on Mar. 26, 1986 and corresponding to U.S. Pat. No. 4,694,540. However, the apparatus disclosed is of complicated and expensive design.
A somewhat simplified form of can filling apparatus of this general kind is also known from DE-OS 33 18 944, laid-open on Nov. 29, 1984 and corresponding to U.S. Pat. No. 4,545,093. The design of this device is less complex. However, the design that has been selected leads to an undesired loading of the fiber band so that band breakages can occur, particularly when the machine has been in use for a long period of time and wear has led to undesired play in the individual elements.
In the design of DE-OS 33 18 944 the axle which carries the friction wheel is pivotably (i.e. hingedly) supported at its end opposite to the friction wheel and a compression coil spring arranged beneath the axle attempts to pivot the axle upwardly and thereby hold the friction wheel in engagement with the horizontal ring surface of the head part on which it rolls in operation. Wear of the friction wheel and tolerances in the design are compensated for by this spring. The friction wheel and the one calender roller form a hollow unit which is rotatably journalled on a pivotable axle. This unit also contains a gear wheel which meshes with a further gear wheel which drives a second calender roller. In this way the axle of rotation of the second calender roller is fixedly arranged on the rotary plate. With this design the guidance of the pivot axle causes certain problems which in operation lead to the mutual spacing between the two calender rollers no longer remaining constant, in particular when a certain amount of wear has occurred. Thus the clamping of the band or sliver between the two calender rollers leaves something to be desired.
Moreover, deflection movements of the pivotally journalled axle about its pivot axis also lead to a change of the clamping force and, via the intermeshing gear wheels also to a variation of the speed of rotation of the two calender rollers, which is also undesirable. Furthermore, the layout of the friction wheel with a horizontally extending surface is unfavorable because the friction wheel itself is deformed by this design as the circumferential speed of the radially inner edge of the friction wheel must be lower than the circumferential speed of the radially outer edge of the friction wheel, with the expression "radial" being understood here in relation to the axis of rotation of the rotary plate. The continuous deformation of the friction wheel as a result of this design necessarily leads to premature wear of the friction wheel which increases the already mentioned difficulties in the area of the calender rollers.
With such a complicated design a constant loading of the fiber band cannot always be achieved in the clamping region between the calender rollers, and there is a danger of band breakages, particularly after the wear which occurs in long term operations.